ASUS A88X-PLUS documentation in a 580 KB RAR archive, for an ATX board with the AMD A88X chipset and the FM2+ socket. What exactly is inside is not given by the name; a boardview, schematic or both are most likely. They help a technician locate MOSFETs and PWM controllers, trace nets to find shorts and identify test points for the power sequence. Extract the files with 7-Zip or WinRAR, and confirm the board revision before relying on them.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @boardview. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.
7-ZipWinRARThe Unarchiver (macOS)